1. Technical Field
The invention relates to an electronic device, more specifically, relates to a semiconductor memory device and an operating method thereof.
2. Related Art
A semiconductor memory device is a memory device using a semiconductor such as silicon (Si), germanium (Ge), gallium arsenide (GaAs), indium phosphide (InP), or the like. The semiconductor memory device can be classified as a volatile memory device and a nonvolatile memory device.
The volatile memory device is a memory device which loses stored data when a power supply cuts off. The volatile memory device includes a static RAM (SRAM), a dynamic RAM (DRAM), a synchronous DRAM (SDRAM), or the like. The nonvolatile memory device is a memory device which maintains stored data even when a power supply cuts off. The nonvolatile memory device includes a read only memory (ROM), a programmable ROM (PROM), an electrically programmable ROM (EPROM), an electrically erasable and programmable ROM (EEPROM), flash memory, a phase-change RAM (PRAM), a magnetic RAM (MRAM), a resistive RAM (RRAM), a ferroelectric RAM (FRAM), or the like. The flash memory can be classified as a NOR-type and a NAND-type.
Recently, in order to improve a degree of integration of the semiconductor memory device, a semiconductor memory device having three-dimensional array structure has been studied.